I am 25 years old i'm having recurrent mouth ulcers which occurs mostly on the lips, chicks and tip of the tongue. These ulcers are small, round in shape heal themselves after a week or a week and half ,the ulcers disturbs speaking and eating .I was tested for several diseases including syphilis, burucelosis and hiv all of them were negative. This problem is stabbing my mind what could be the problem.